Well, Kakashi could train Naruto in combat skills specific to ANBU missions. This would include more lethal and precise attacks. He might also teach Naruto how to use different types of weapons that are common in ANBU operations. Maybe Kakashi would set up mock battles where Naruto has to face multiple opponents at once, just like in real ANBU scenarios.
In a fanfiction, Kakashi's past in ANBU could be the backdrop for a story where Sakura is on a mission and gets in over her head. Kakashi, using his past experiences and skills from the ANBU days, comes to her rescue. This could lead to a deepening of their relationship as he imparts some of his hard - earned wisdom to her.
There are 'anbu kakashi fanfic' stories that take a different approach. They might create alternate universes where Kakashi's time in ANBU has different outcomes. For instance, what if he had a different mentor during his ANBU days? This can lead to all kinds of unique storylines and character developments.
They would probably have a very close and mentor - student relationship. Kakashi, being Naruto's caretaker and trainer, would be like a father figure to him. Naruto would look up to Kakashi and trust his guidance completely.
One idea could be exploring Kakashi's relationships within the Anbu. For example, his friendships or rivalries with other members. Maybe there was a particular mission where he had to rely on a teammate he didn't trust at first.
Definitely Obito. Since they have a long - standing connection, it would be interesting to see how their relationship played out during Kakashi's Anbu days. Maybe Obito was still alive and had his own secret missions within the Anbu that intersected with Kakashi's.
The plot could involve Sakura finding a mysterious artifact related to Kakashi's ANBU days. As she tries to figure out its significance, she has to seek Kakashi's help. This brings them closer as they explore the secrets of his past together.
One common theme is redemption. Since Kakashi has a lot of regrets in his life, in time - travel fanfics, he often tries to make up for his past mistakes. For example, he might try to save his comrades who died in the original timeline.
I really like 'Back to the Beginning: Kakashi's Time Travel'. In this fanfic, Kakashi travels back to his early days in the Anbu. It's interesting to see how he interacts with his younger self and how he tries to prevent some of the mistakes he made in the past. The author does a good job of keeping the Naruto universe's lore intact while adding their own unique twists.
He may be surprised. Fanfictions can have some really out - there ideas that he might not have considered before. For instance, a fanfiction might have Naruto suddenly having a new, super - powerful jutsu that was never seen in the original series.